Ectopic pregnancy.

Ectopic pregnancy is a potentially lethal disorder that is often difficult to diagnose clinically. More than 70,000 ectopic pregnancies are reported annually in the United States, and the incidence is rising. A thorough knowledge of predisposing factors, clinical presentation, common misdiagnoses, and recent advances in diagnostic modalities should help the Emergency Department physician avoid the pitfalls that lead to misdiagnosis with resulting morbidity and, occasionally, mortality.